The present invention relates to an apparatus for emptying and recharging a refrigeration system and of the type which comprises a discharge container for drawn-off polluted refrigerant, a charging container for clean refrigerant to be charged, pump means, means for metering the refrigerant to be charged and conduit means comprising closing valves and arranged for connecting the refrigeration system and the elements forming part of the apparatus.
Such apparatus is used for servicing refrigeration systems which are for example used for the refrigeration or cooling of foods, air conditioning and other systems wherein a refrigerant is compressed, expanded and condensed.
When servicing a refrigeration circuit, it has been customary to ventilate the circuit thus discharging the polluted refrigerant into the atmosphere. However, this has become unacceptable, and apparatus of the above-mentioned type for servicing refrigeration systems have been manufactured. Examples of such apparatus are known, e.g. from U.S. Pat. Nos. 4,363,222 and 4,364,236. The apparatus disclosed in these patents are associated with problems relating to the risk of contaminating the refrigerant charged. Moreover, the amount of refrigerant used in said apparatus will be inaccurate and thus said apparatus will not permit minimization of refrigerant consumption and simultaneous charging of such an accurate amount which is necessary in order not to damage the compressor and in order to obtain good operation efficiency.
The requirements for accurate recharging are becoming increasingly important as environmental considerations force the producers to reduce the consumption of refrigerant, especially the consumption of freon. When new types of freon, e.g. R134A, is marketed, the price level is expected to increase by approximately 10-15 times the present level for refrigerants. Thus the price will induce a requirement for minimizing refrigerant consumption.
It is an object of the invention to provide an apparatus and a method for easy and safe emptying and recharging a refrigeration system, which makes it possible to minimize refrigerant consumption.
A further object of the invention is to provide a portable apparatus for emptying and recharging a refrigeration system, which apparatus is useful for on-site servicing and for an automatic sequence of operations for emptying and subsequently recharging an accurate amount of refrigerant.
It is another object of the invention to provide an apparatus for emptying and recharging a refrigeration system wherein the refrigerant condensation and the evaporation processes support each other when emptying the refrigeration system.
It is a further object of the invention to provide an apparatus for emptying and recharging a refrigeration system wherein only one compressor is required for the removal of polluted refrigerant and evacuation of the refrigeration system.
It is yet another object of the invention to provide an apparatus and a method for emptying and recharging a refrigeration system wherein a gaseous pressurized refrigerant is charged to said system, which gaseous refrigerant is produced by heating clean liquid refrigerant.
According to the present invention the above-mentioned apparatus is provided wherein the discharge container comprises a storage chamber for liquid refrigerant and a suction chamber, which are established in a mutual heat exchanging relationship, wherein the charging container comprises a storage chamber for liquid refrigerant and a metering chamber, which are established in a mutual heat exchanging relationship, wherein the pump means consist of a compressor, which, through the conduit means, is arranged between the chambers of the discharge container by an appropriate setting of the closing valves and which, through another setting of the closing valves, is arranged between the refrigeration system and the atmosphere in order to evacuate the refrigeration system, wherein the storage chamber of the charging container comprises a heating element for heating the liquid refrigerant, wherein a connection is provided between the storage chamber and the metering chamber for introducing a gaseous refrigerant into the metering chamber, wherein said connection is provided with means for metering the pressure and for cutting off the connection when a predetermined pressure is obtained and wherein the conduit means establish a connection between the metering chamber and the refrigeration system for charging clean pressurized refrigerant.
The method according to the invention wherein an apparatus of the above-mentioned type is used comprises the steps of
emptying refrigerant from the refrigeration system as pump means in the form of a compressor draw refrigerant into a suction chamber in the discharge container, PA1 transmitting the gaseous refrigerant through the compressor to a storage chamber arranged in the discharge container in which storage chamber the refrigerant is condensed, PA1 automatically disconnecting the compressor when the refrigerant has been discharged, PA1 changing the position of the closing valves in order to evacuate refrigerant from the refrigeration system as the compressor, when blowing off into the atmosphere, creates a vacuum in the refrigeration system, PA1 evaporating clean refrigerant contained in the storage chamber of the charging container, PA1 conducting the gaseous refrigerant into the metering chamber of the charging container, PA1 using the evaporated and pressurized refrigerant for flushing the refrigeration system and transmitting said refrigerant through the compressor to the discharge container, PA1 evacuating again refrigerant from the refrigeration system, PA1 charging clean refrigerant into the refrigeration system as gaseous refrigerant is introduced into the metering chamber until a predetermined pressure is reached and the pressurized refrigerant has flowed into the refrigeration system after the position of the closing valves has been changed, and PA1 charging and emptying the metering chamber in a corresponding way until a predetermined number of cycles have been effected whereby a well-defined amount of refrigerant has been charged to the system.
In the practice of the invention, the apparatus is coupled to an emptying stub of the refrigeration system according to any method well-known to a person skilled in the art.
The apparatus comprises several elements which are mutually connected by means of conduits comprising electrically and/or manually operated valves. Moreover, the apparatus comprises known monitoring and control equipment providing information to a pre-programmed microprocessor. The microprocessor is built into a control box effecting automatic control of different operation sequences which are chosen by the operator. However, such further equipment is well-known to the person skilled in the art and is not illustrated herein.
When a connection has been established between the apparatus and the refrigeration system, the following sequences for emptying and recharging are conducted in a closed circuit. This provides good security against undesired spill of refrigerant. During the discharging and evacuation, only a compressor is used. This simplifies the apparatus as compared to the prior art, apparatus which uses both a compressor and a vacuum pump. The compressor is arranged between the two chambers of the discharge container which is situated in an insulated unit. Hereby the evaporation process, which takes place in the suction chamber, is supported by the condensation process which takes place in the storage chamber. In this way it is possible to reduce the energy consumption and to accelerate the discharging. By activating the control box, it is possible to switch the closing valves and during the following charging, the heating element is used to produce gaseous refrigerant. As the metering chamber and the storage chamber of the charging container are in a heat exchanging relationship inside an insulated unit, it is possible to maintain the temperature of the gaseous refrigerant constant. Together with a specific differential pressure existing for the metering chamber, the constant temperature makes it possible to establish a high degree of accuracy even when charging small amounts.